Golden State Warriors' David Lee drives toward the basket as Boston Celtics' Brandon Bass defends during the first half of an NBA basketball game in Oakland, Calif., Saturday, Dec. 29, 2012. (AP Photo/George Nikitin)

Photo: George Nikitin, Associated Press

Golden State Warriors' David Lee drives toward the basket as Boston...

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Boston Celtics' Courtney Lee, front, rebounds in front of Golden State Warriors' Andris Biedrins, behind left and Carl Landry, during the first half of an NBA basketball game in Oakland, Calif., Saturday, Dec. 29, 2012. (AP Photo/George Nikitin)

Photo: George Nikitin, Associated Press

Boston Celtics' Courtney Lee, front, rebounds in front of Golden...

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Boston Celtics head coach Doc Rivers talks to an official during the first half of an NBA basketball game against the Golden State Warriors in Oakland, Calif., Saturday, Dec. 29, 2012. (AP Photo/George Nikitin)

Golden State Warriors forward David Lee (10) right is called for an offensive foul against Boston Celtics Jared Sullinger (7) in the first half of their NBA basketball game Saturday, Dec. 29, 2012 in Oakland, California.

Photo: Lance Iversen, The Chronicle

Golden State Warriors forward David Lee (10) right is called for an...

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Golden State Warriors Jarrett Jack (2) right drives to the basket against Boston Celtics Brandon Bass (30) in the first half of their NBA basketball game Saturday, Dec. 29, 2012 in Oakland, California.

Photo: Lance Iversen, The Chronicle

Golden State Warriors Jarrett Jack (2) right drives to the basket...

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Golden State Warriors forward David Lee (10) shoots in front of Boston Celtics Jeff Green (8) in the first half of their NBA basketball game Saturday, Dec. 29, 2012 in Oakland, California.

Golden State Warriors' Stephen Curry, foreground, looks for a receiver under the arm of Boston Celtics' Jason Collins during the first half of an NBA basketball game in Oakland, Calif., Saturday, Dec. 29, 2012. (AP Photo/George Nikitin)

Apparently, Boston's Paul Pierce was on the rookie's "big game list," too.

Barnes played arguably his most aggressive and complete game since mid-November, outplaying the future Hall of Famer and instigating the Warriors' 101-83 victory Saturday night in front of Oracle Arena's fifth consecutive sellout crowd.

"He makes us better," Jackson said. "Harrison did a very good job of making Paul Pierce work for his shots. You're not going to stop him, but (Barnes) stayed in the picture and contested shots.

"He was in attack mode and got it going, offensively. We need him to do that, whether he's playing five minutes, 20 minutes, 30 minutes or 40 minutes. We need him to be in attack mode at all times."

The Warriors (21-10) have won 14 of their past 18 games and completed a 12-win December that tied the franchise record set in 1961. During their West Coast era, the Warriors have won 12 games in any month only four times and haven't done it since going 13-4 in March 1976.

The Celtics (14-15), who had beaten the Warriors in seven of the teams' past eight meetings, were playing without NBA assists leader Rajon Rondo, who has a bruised right hip. Though the Warriors were the team playing a back-to-back, Boston was the one that looked old and tired.

Especially when compared to the 20-year-old Barnes, whose fresh legs and athleticism bothered Pierce all night. Pierce missed his first eight field-goal attempts and finished with 13 points on 4-of-20 shooting.

Barnes responded to playing only 16 minutes in each of the past two games by rediscovering some aggression. He had 15 points on 5-of-6 field-goal shooting and added eight rebounds to the energetic defense he displayed throughout his 26 minutes.

"There are people in his situation who would love to be playing 40 minutes, getting a bunch of isolations and post-ups," Jackson said. "Well, there are some rookies doing that, and they've got single-digit wins. (Barnes) is part of something very special, and it's going to put him in a position to become, not a good player, but an exceptional one.

"He's going to look back and embrace the foundation that was laid for him as a rookie."

After averaging only 6.3 points on 31.8 percent shooting and 2.3 rebounds during the past six games, Barnes seemed to make a point of looking for his shot early against Boston. It was one of the first times he wasn't noticeably deferring to his more experienced teammates since a 20-point, 12-rebound night in Dallas on Nov. 19, and it ended up opening things up for other Warriors.

For the 11th time this season, they outshot, outrebounded and out-assisted an opponent on the same night. They haven't completed the triple more times in a full season since 2007-08, when they did it 12 times in their last winning season.

Jackson said, "2012 has been real good to us, and we will put it behind us and look forward to doing great things in 2013. I really believe that bigger things lie ahead than what we just accomplished."